Locally advanced cervical cancer: Is it relevant to report image-guided adaptive brachytherapy using point A dose?

Renaud Mazeron; Sebastien Gouy; Alexandre Escande; Isabelle Dumas; Eleonor Rivin Del Campo; Enrica Bentivegna; Warren Bacorro; Dimitri Lefkopoulos; Eric Deutsch; Philippe Morice; Christine Haie-Meder; Cyrus Chargari

doi:10.1016/j.brachy.2017.04.244

Locally advanced cervical cancer: Is it relevant to report image-guided adaptive brachytherapy using point A dose?

Brachytherapy. 2017 Jul-Aug;16(4):862-869. doi: 10.1016/j.brachy.2017.04.244. Epub 2017 May 24.

Affiliations

¹ Department of Radiation Oncology, Gustave Roussy, University Paris-Saclay, Villejuif, France; Molecular Radiotherapy-UMR 1030, Gustave Roussy, France.
² Department of Radiation Oncology, Gustave Roussy, University Paris-Saclay, Villejuif, France.
³ Department of Medical Physics, Gustave Roussy, University Paris-Saclay, Villejuif, France.
⁴ Molecular Radiotherapy-UMR 1030, Gustave Roussy, France; Department of Medical Physics, Gustave Roussy, University Paris-Saclay, Villejuif, France.
⁵ Department of Surgery, Gustave Roussy, University Paris-Saclay, Villejuif, France.
⁶ Department of Radiation Oncology, Gustave Roussy, University Paris-Saclay, Villejuif, France; Molecular Radiotherapy-UMR 1030, Gustave Roussy, France; French Armed Biomedical Research Institute, Brétigny sur Orge, France. Electronic address: cyrus.chargari@gustaveroussy.fr.

PMID: 28551312
DOI: 10.1016/j.brachy.2017.04.244

Abstract

Purpose: To evaluate the usefulness of reporting the point A dose in patients with locally advanced cervical cancer treated with image-guided adaptive brachytherapy (IGABT).

Methods and materials: Dosimetric data from patients treated with a combination of chemoradiation and intracavitary IGABT were examined in light of their outcomes. Prescribing followed the Groupe Européen de Curiethérapie-European Society for Radiation Oncology recommendations. All doses were converted in 2-Gy equivalent. The relationships between the D90 high-risk clinical target volume (CTV_HR) and intermediate-risk clinical target volume (CTV_IR) and point A doses were studied. Dose-effect relationships based on the probit model and log-rank test were assessed.

Results: Two hundred twelve patients were included with a median followup of 53.0 months. A total of 28 local relapses were reported, resulting in a local control rate of 86.6% at 3 years. Mean D90 CTV_HR, CTV_IR, and point A doses were: 79.7 ± 10.4 Gy, 67.4 ± 5.8 Gy, and 66.4 ± 5.6 Gy, respectively. The mean D90 were significantly different and independent from the mean point A dose, even in bulky tumors at diagnosis or in large CTV_HR lesions. Point A dose appeared correlated with TRAK, and finally with the D90 CTV_HR through a complex formula including the CTV_HR volume (R² = 0.55). Whereas significant relationships between the probability of achieving local control and the D90 CTV_HR and CTV_IR (p = 0.08 and 0.025) were observed, no similar relationship was found with point A dose except a trend of an inverse relation. After sorting patients according to three dose levels, highest local control rates were observed in patients with D90 CTV_HR ≥85 Gy, whereas those with point A doses ≥70 Gy had the worst outcomes.

Conclusions: In patients treated with IGABT, point A dose is not predictive of local control but a surrogate of the irradiated volume. Its relationships with the D90 CTV_HR are indirect and complex rising the question of relevance of its reporting in routine.

Keywords: High-risk clinical target volume; Image-guided adaptive brachytherapy; Point A; Tumor control probability.